The present invention relates to a method of forming a ceramic mold for metal casting, and more particularly to a method of forming a ceramic mold for producing metal castings for products such a golf club heads.
Various methods of forming ceramic molds for metal casting are well known in the art. Traditional investment casting involves the "lost wax process". In the process, substantial time-consuming preparation of the mold is required, including the initial welding of the wax patterns to a gate and then the laborious lost wax mold building process. The resultant mold typically lacks the high strength which is required in order to permit very fine details, such as grooves, lettering or other features, to be incorporated into the metal casting, thus requiring such features to be added later through additional processing. A further disadvantage of the lost wax process is that the mold built up about the wax cannot be visually inspected to insure that, when used, the resultant metal casting will be of the appropriate configuration and dimensions.
In another method, the ceramic molds are made by pouring a slurry of ethyl silicate and a refractory ceramic to form two mold halves and then "booking" or assembling the two mold halves together to form the mold. This method is not only labor intensive and hence very expensive, but also fails to provide adequate dimensional control and alignment of the mold halves. Accordingly, the method is not well suited for forming a ceramic mold for metal castings having precise dimensions.
Another process, developed originally for the casting of turbine blades, involves forming a plurality of ceramic mold sections--one section to mold one outer part of the blade, another section to mold the interior of the blade, and a third section to mold the other outer part of the blade--with the individual mold sections being made by injection molding or some other ceramic core process. The mold suffers from a tolerance buildup that does not permit sufficient dimensional control along parting lines of the mold; accordingly, again, the method is not well suited for the production of ceramic molds for metal castings of precise dimensions.
Accordingly, it is an object of the present invention to provide an improved method of forming a ceramic mold for metal casting suitable for producing metal articles of precise dimensions.
Another object is to provide such a method which requires only a minimum of mold preparation.
A further object is to provide such a method which can be performed in a small, confined area at a rapid rate, with the mold being ready for casting in less than 24 hours.
It is another object of the present invention to provide such a method in which the resultant mold is of high strength, permitting fine detail to be incorporated into the metal casting.
It is also an object to provide such a method which permits the mold pieces to be inspected prior to casting.